Balancing S38 ITBs

Specific conversations and info for the BMW E28 M5 and M535i.
Randomg
Posts: 480
Joined: Jul 12, 2007 3:12 PM
Location: Seattle

Re: Balancing S38 ITBs

Post by Randomg »

Tried again today, followed tn535i's plan, set all the screws to default and used the butterfly stoppers to get them as close as possible first, then tuned with the bypass screws. When I was done and had the right vacuum on the gauge (little less than 30) and all of cylinders at the same place, I was back to where I was yesterday, which is that my idle was still too high.

With the tps connector jumpered, the idle speed was right around 1000 like you had suggested. This was with the cylinder one bypass screw tightened all the way and the 1-2 stopper set to right as it started to move from resting against the intake manifold (I can probably get it more closed with a dial indicator instead of eyeing it, which I'll do tomorrow). I also had the idle speed screw tightened down all the way. I expected to see the idle drop when plugging the connector back into the tps, maybe my idle system isn't working right, I guess I'll check the tps is grounding correctly tomorrow as well.

Not really sure what's going on, I'll go in with a dial indicator tomorrow to make sure the 1-2 set are as close to closed as possible and try again.

I think you're right about WOT, but even if you weren't, I don't care anymore, I'd rather have a good idle than a perfect WOT at this point.
tn535i
Posts: 5585
Joined: Jul 14, 2006 1:30 PM
Location: Middle Tennessee

Re: Balancing S38 ITBs

Post by tn535i »

When the TPS closes at idle is it changing anything? It sounds like you should test it next to be sure you're getting an idle input. First check for voltage at the outer pins, 5vDC IIRC, and then the center pin should be ground (0v) on the connector. Backprobe the connector and plug it back in the TPS and 5v on the idle input (pin 1 I think) must go to 0v when the throttles are closed for idle control. It may just need adjustment or maybe the switch is bad. I've seen several of these TPS have bad solder connections inside after years of thermal cycles.

Idle control on the S38 has always been a bit of a mystery to me and I would not be surprised if some act differently depending on the chip (most are chipped). If the idle loop can 'control' why do you need to adjust the bypass screw on the t/b's anyway. Balancing the t/b's make sense but not adjusting idle. My big screw seems to do little when the TPS is active. In fact I've always thought maybe the instructions I've seen were wrong and should tell you to first unplug the TPS then use the big bypass screw to set the warm idle up to about 900-1000 so that when you plug the TPS back in it controls properly. Sometimes this is in essence what I do. Then when I plug the TPS back in the idle drops a little to about 800. But maybe that's my specific chip ?

Not sure how you would adjust perfect WOT, almost no vacuum and really 80-90% open is probably flowing the same air as 100% open. Above 3500 rpm or so the S38 is just open loop and dumping fuel in based on the AFM and speed map, and making nice sounds. I think if you do get idle right the rest will be fine.
Randomg
Posts: 480
Joined: Jul 12, 2007 3:12 PM
Location: Seattle

Re: Balancing S38 ITBs

Post by Randomg »

Went through the whole procedure (I guess I should have done that in the first place) and had better luck. I was able to get my idle down to around 1000 with throttles sync'd at the right vacuum. I think my idle control valve isn't working correctly at this point, but I think I should be ok to fix that later and use the large bypass screw to adjust if necessary without ruining the vacuum syncing of the individual screws. Cylinder 1 and the large bypass screws are tightened all the way, but I guess that's fine if all the measurements are right.

What I meant by perfect WOT is that all butterflies are at the correct angle when resting against the WOT stopper.

For what it's worth tn535i, tuning the idle by the butterfly stoppers didn't end up working well for me. During my drive the on/off throttle transition was worse and my wideband showed noticeably different AFRs at part throttle. Maybe my engine required more variation between the throttles than yours did?

I'll be shipping it back to Healey tomorrow.
tn535i
Posts: 5585
Joined: Jul 14, 2006 1:30 PM
Location: Middle Tennessee

Re: Balancing S38 ITBs

Post by tn535i »

This S38 is a tricky beast IMO. Not the smoothest idle and basically ready to make power with just a crack of the throttle. Isn't that what the ITB's are all about.

It sounds like something isn't right with your idle control though. Maybe the TPS or maybe a sticking or bad ICV? For example, unplug your TPS and see if any on/off idle transitions disappear or anything changes, mine will do that. But when the TPS and ICV are active some slight transitions can happen as you go off idle and the ICV goes back to a home or neutral position. I find it worse on deceleration.

The procedure as I read would have you probably set the t/b's for a slightly open or higher idle with TPS unplugged. Opening the big bypass screw will let more air through and should make the computer close the ICV. If the ICV is quite closed and then goes back to about 1/2 as it comes off idle control at the same time the throttle opens it might make for a bigger bump in speed that you want. Is that what you have now?

If the ICV is more open and closes as it comes off idle you might even get a dip in speed. In this case you will also get a bit more engine break if you close the throttle while in gear as the computer tries to close the ICV all the way down to reduce speed but the drivetrain is trying to turn the engine faster. You'll feel that when you lift off throttle in gear. If the ICV is too far open on normal idle it won't have the range it needs for a cold idle either. So this probably worse than the previous.

Somewhere in between is the best compromise. I'm not sure there is a complete win on the S38 as the computer only knows to try to control or not control idle and the range of the ICV is what it is. I don't think there is any logic for anything based on road speed or gear ratio like a newer car. It may take some experimentation to find the sweet spot you like.

I've been tempted to put a scope on the ICV and watch it's open/close times and transitions. That might be a better way to get the base throttle set about right on a warm engine and then balance from there.

Also, I think as long as you don't adjust the t/b stops or individual bypass screws you are not going to loose your balance made. And what I meant on WOT is the minute adjustments at idle mean almost nothing at WOT, certainly < a 1 degree at idle and the difference of 99% vs 100% is nothing at WOT.
Pattonky
Posts: 127
Joined: Dec 26, 2011 10:28 AM
Location: Richmond, KY

Re: Balancing S38 ITBs

Post by Pattonky »

I just got through syncing my throttle bodies with a carb tuner. Only 1 and 6 were off at all. 1 was a little high and 6 was a little low. This made a big difference in the idle. The car seemed to kind of cycle before the adjustment and the idle fluctuated from about 870 to as high as 1050. After adjustment she rides more steady between 890-950. I don't think the adjustment of the throttle bodies altered the RPM so much as it allowed the motor to maintain a more constant rpm. RPM taken with Fluke 88. I suppose I am just kind of posting with the hope that this might be useful info to somebody.
bobby in Derby City
Posts: 980
Joined: Feb 12, 2006 12:00 PM
Location: Hidin' in a bowl of rice ready to put a cap in an a$$

Re: Balancing S38 ITBs

Post by bobby in Derby City »

Pattonky wrote:I just got through syncing my throttle bodies with a carb tuner. Only 1 and 6 were off at all. 1 was a little high and 6 was a little low. This made a big difference in the idle. The car seemed to kind of cycle before the adjustment and the idle fluctuated from about 870 to as high as 1050. After adjustment she rides more steady between 890-950. I don't think the adjustment of the throttle bodies altered the RPM so much as it allowed the motor to maintain a more constant rpm. RPM taken with Fluke 88. I suppose I am just kind of posting with the hope that this might be useful info to somebody.
Fluke 88 and a carb tuner!! I should come down I-64East to see ya so we can do mine :D ...
Pattonky
Posts: 127
Joined: Dec 26, 2011 10:28 AM
Location: Richmond, KY

Re: Balancing S38 ITBs

Post by Pattonky »

Are you having trouble with your idle or are you just pulling my chain over the tools to do the work? I will confess that I am a believer in having good tools to work with when I do something.
milarsky
Posts: 515
Joined: Jan 26, 2013 11:19 AM
Location: NYC

Re: Balancing S38 ITBs

Post by milarsky »

Dean,

I was lucky enough to meet Alim this summer, who lives in ABQ. I am in Santa Fe for the summer. He currently is tuning his throttles using your Mantis. We threw it on my car, which runs very well. The throttles were very uneven and after 5 minutes of adjusting them, it was amazing. The thing runs like a scorned dog! What a difference. I cannot thank you enough for sending this thing around. Now we are working on Alim's car, on which we have some baselining to do over this next week.
Many thanks,
jeff
alim_h
Posts: 58
Joined: Mar 09, 2015 3:10 PM
Location: Albuquerque, NM

Re: Balancing S38 ITBs

Post by alim_h »

Thank you Dean. I just finished getting my throttles adjusted too! Worked out very well and I did notice a difference at idle and just off idle.

The Mantisometer was simple to set up and use - genius idea! Thanks for loaning it out.

I have some pics and videos here: https://www.dropbox.com/sh/sh8u2e3g8gmu ... ZISJa?dl=0
HealeyBN7
Posts: 251
Joined: Feb 06, 2009 5:22 PM
Location: Thousand Oaks, CA

Re: Balancing S38 ITBs

Post by HealeyBN7 »

Great to hear that it worked out. After getting it back I replaced the tubing as it started to yellow and took it and my M5 to the SoCal Vintage BMW meet for a little show and tell. Hooked it up to a couple S38s but the owners weren't brave enough to turn any screws. I don't blame them. Parking lot tuneups never end well. You really need to work through the mechanicals (valves and throttle plates) first. This is the last step.

It was sent to Matt - Defacto in CT after the show. UPS says it arrived on the Oct 13th. Matt, if you see this message, or the PM or my email, can you confirm that you do indeed have it and let me know when you are planning to return it.

Of course if you have any questions post them here or PM/email me.

Thanks,
Dean
MicahO
Posts: 2481
Joined: Jan 07, 2010 7:50 AM
Location: Warwick, NY

Re: Balancing S38 ITBs

Post by MicahO »

Hi Dean - if it's made it out to the East Coast and doesn't have another date booked, perhaps I can pick it up from Matt and go through the process with my e28. Maybe even the Touring? Should be physically the same process, I think.....

Maybe get a balancing-fest together? November gets relatively open, in-between sports seasons for the kids means the weekends open up a little.....
MicahO
Posts: 2481
Joined: Jan 07, 2010 7:50 AM
Location: Warwick, NY

Re: Balancing S38 ITBs

Post by MicahO »

So I'm done with the use of the Mantismanometer on both the e28M5 (s38B35) and the e34 M5 Touring (S38B38), and it went very well! I went through cleaning the needle valves and new orings, valve adjustment and butterfly settings in the run-up to the Mantis' arrival. I had also roughly set the vacuum on each intake with a gauge - new Oring, full-tight, then out one turn, then set to a rough-bouncing-about-9-inches-of-vacuum with a gauge and a pinched hose. Even that was an improvement for both cars. Then with the Mantis local and a couple of decent weather days I got the real balancing act done.

The touring started fairly balanced right from the rough-set of one-turn-out. On the e28 I did end up moving the screws more than I thought I would to attain leveled readings. The e28's screws were highly variable before I removed them, two almost totally closed and one about 1.5 turns out (that was the factory set with yellow caps). Position isn't what matters, the level of vacuum is, but it did seem strange that there was so much variance in how tight the needle was set.

Also, I'm really not sure what I was smoking, but I did connect the hoses 1-2-3-4-5-6 front to back on both cars, and I'm almost certain that when I adjusted the touring, the cylinder 1 port moved the right-most line of fluid, and on the e28 it adjusted the left-most. :shock: :roll: :? :laugh:

Either way, I got both cars nicely set. The e28 in particular is now more manageable on-off throttle than it had been, and has back all of the immediate off-idle 'pop' that it had been missing after a tank of bad gas on the way home from TedFest in June. It's FAR smoother idling around at parking-lot speeds, and even sounds better. The B38 in the Touring is a far different engine management, which may be why the difference is not *as* noticeable, but there is still a notable improvement all-around.

Really great tool, and MANY THANKS TO DEAN for making it available to the community!

If there is anyone relatively local (NY Tri-State) that wants to do a round of tuning please let me know ASAP. Dean has someone lined up on the Left Coast as the next destination. If I don't hear from anyone semi-local in the next week or so I'll send it westward-ho!
Valve_clatter
Posts: 39
Joined: Oct 27, 2016 6:21 PM
Location: Kansas

Re: Balancing S38 ITBs

Post by Valve_clatter »

Now that I have finally finished with the exhaust, and purchased all the requisite other bits means I actually should probably do this...
BenGerman
Posts: 740
Joined: Jun 26, 2016 2:19 PM
Location: MA

Re: Balancing S38 ITBs

Post by BenGerman »

What is the current schedule for the Mantismanometer?
Any chance to get a hold of it before the Vintage?
HealeyBN7
Posts: 251
Joined: Feb 06, 2009 5:22 PM
Location: Thousand Oaks, CA

Re: Balancing S38 ITBs

Post by HealeyBN7 »

Ben,

chances are good. It is ready to ship. Send me your contact information (real name, shipping address, phone number, etc) off line and I'll get it in the mail this week.

I have had to refurb the unit a few times, so if I am pivoting off the free rental program to now include a use fee to cover incidentals.

2017 pricing is as as follows:

$25 to get it shipped out.(USPS) plus,
$100 deposit (includes use fee) for a total of,
$125 due at time of rental (pal pay to healeybn7@yahoo.com)

Two week rental time unless agreed-to up front.

You will have to pay for shipping it back to me and when returned, you will receive $75 back on paypal.

I can send you an updated pdf that includes corrections and tips from others. Be sure to read the pdf before ordering the Mantis as you may want to have a set of o-rings on hand before starting. This is the last step in the tuning process, so valves should be dialed in before hand as well.

Dean
BenGerman
Posts: 740
Joined: Jun 26, 2016 2:19 PM
Location: MA

Re: Balancing S38 ITBs

Post by BenGerman »

I will not need it before the end of April, so it doesn't make sense to get it this exact moment.
Hope a couple more people can squeeze in before me. End of April/ beginning of may would be perfect. I will keep following in here!
HealeyBN7
Posts: 251
Joined: Feb 06, 2009 5:22 PM
Location: Thousand Oaks, CA

Re: Balancing S38 ITBs

Post by HealeyBN7 »

BenGerman wrote:I will not need it before the end of April, so it doesn't make sense to get it this exact moment.
Hope a couple more people can squeeze in before me. End of April/ beginning of may would be perfect. I will keep following in here!
If you set your throttle plates ahead of time, another option is to meet up at Vintage (assuming it is the So Cal Vintage in Woodland Hills) and tune it "live on the grass".

I just wanted to clarify my thoughts about the change in deposit. The ~$20 use fee isn't intended to discourage anyone from borrowing the tool. After paypal fees and rounding it probably nets to $15 and I would be happy to reconsider if with a little encouragement.

It has been borrowed a lot over the past few years. Shipping is supposed to be smooth but stuff just seems to happen to it as it moves around.

There was a time where the unit was dropped off at a UPS store, mislabeled and sent to the wrong address. Thankfully I received a box of jerseys that were meant for someone else and we eventually exchanged packages. And then there was a time when the box arrived open and the dial indicator was missing... and then there was a time when the oil cap wasn't screwed on and it looked like a box of donor organs...

Let me know what works for you. Happy to help.

Dean
keeper
Posts: 4
Joined: Jul 16, 2016 8:27 PM
Location: Colombia South America

Re: Balancing S38 ITBs

Post by keeper »

I know it´s been tow years since your post, but I´m just getting to adjusting the ITBs in my E28 ///M5; which by the way it´s the only one in existence in Colombia, South America. It´s been kinda rough restoring this monster due to the unavailability of parts, not to mention knowledge about this specific subject. Anyway, I want to thank all those who took part in this conversation; I was delightfully enlightened on the subject. By the way, I have installed a Megasquirt II module.
HealeyBN7
Posts: 251
Joined: Feb 06, 2009 5:22 PM
Location: Thousand Oaks, CA

Re: Balancing S38 ITBs

Post by HealeyBN7 »

Just a quick update on the Mantis Manometer.

Since putting it together a couple years ago and making it available for enthusiast use, it has been in almost constant circulation. It came as a surprise to me that some of you would like to have your own manometers, so I built a few for enthusiasts and shops.

The current "rental unit" was refurbished a month ago and I guess it was nice enough that the techs at ACE Performance convinced the boss to buy it instead of sending it back.

Yesterday I ordered enough supplies to make three manometers. I'll keep a rental unit in circulation, build one for myself, and offer one for purchase. While it is a simple device it is time consuming to assemble as a couple parts require machining.

If you are waiting to borrow the tool, Jason Rhee is next in line and will receive a brand new rental. If you want to buy one, check back shortly and I'll post some photos of a finished product and hopefully have a good handle on a price.

Thanks for your support,
Dean
mooseheadm5
Beamter
Beamter
Posts: 23035
Joined: Apr 08, 2009 10:30 PM
Location: Charlottesville, VA
Contact:

Re: Balancing S38 ITBs

Post by mooseheadm5 »

I would be interested in owning one of those and would happily pop them onto the Moosehead site for you to sell if you wanted.
HealeyBN7
Posts: 251
Joined: Feb 06, 2009 5:22 PM
Location: Thousand Oaks, CA

Re: Balancing S38 ITBs

Post by HealeyBN7 »

Paul,

Wow. That is very generous. I'll get cracking on making a few and PM you shortly so we can chat about small print stuff.

Dean
socalM5
Posts: 374
Joined: Jul 28, 2013 1:58 PM
Location: USA

Re: Balancing S38 ITBs

Post by socalM5 »

Great product. Extremely well made these will sell to the S38 enthusiast community very well
Valve_clatter
Posts: 39
Joined: Oct 27, 2016 6:21 PM
Location: Kansas

Re: Balancing S38 ITBs

Post by Valve_clatter »

Would like to hop on the list to get the Mantis Meter, really could use it.
HealeyBN7
Posts: 251
Joined: Feb 06, 2009 5:22 PM
Location: Thousand Oaks, CA

Re: Balancing S38 ITBs

Post by HealeyBN7 »

Valve_clatter wrote:Would like to hop on the list to get the Mantis Meter, really could use it.
PM sent. You are on the list, second in line, but you can buy one and skip the queue:)

Dean
HealeyBN7
Posts: 251
Joined: Feb 06, 2009 5:22 PM
Location: Thousand Oaks, CA

Re: Balancing S38 ITBs

Post by HealeyBN7 »

The new Mantis Manometer is just about ready. Here is a sneak peak before I pack it for Jason.

The R2 version now comes "factory" vacuum tested and calibrated to -292 mBar or ~8.5 inHg. A fill line location is now indicated so no guessing on the fluid volume, and a more compact light weight design should allow you to get it closer to the car. With the preset calibration it will be easier to achieve BMWs average ideal intake specification.

The loaner tool which you are viewing still comes with the breakable hinge pin for easy USPS shipping, but I am assembling a run of tools that are mounted to a single board and can be shipped in a shipping tube.

I am pretty happy with this final design. I'll post some close up photos once they are officially for sale via Moosehead (and yes I still need to call you).

Thank you everyone for your ideas and feedback. We made a good tool together!

Enjoy,
Dean


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